The field of the invention relates generally to DC to DC power converters, and more specifically to DC to DC power converters for use in electrical power systems, for example, in the power systems of vehicles.
Direct current to Direct current (DC-DC or DC to DC) power converters are used in vehicles to step up and/or regulate a voltage. For example, a DC to DC power converter may be used to power an anti-lock brake system (ABS) from a vehicle's main power bus. The voltage of the power bus may vary significantly from a minimum of about 7 volts during engine cranking to a maximum of about 50 volts when systems drawing a load (e.g., headlights) are shut off. If the main power bus is nominally 12 volts, a DC to DC power converter may be used to step up the voltage to 24 volts for ABS brakes. If the main power bus is nominally 24 volts, a DC to DC power converter may pass the bus voltage through to the ABS brakes when the bus voltage exceeds 24 volts and boost the voltage when the bus voltage is less than 24 volts. One type of DC to DC power converter useful in this type of application is a boost power converter. A boost power converter boosts input voltages less than a target output voltage and passes input voltages through that exceed the target output voltage. Boost power converters may be damaged by excessive input voltage or by heat produced when passing an input voltage higher than the target output voltage through to an output of the boost power converter. It is desirable to provide a DC to DC boost power converter which efficiently passes through input voltages in excess of a target output voltage that is protected from input voltages in excess of a target output voltage.